Comparative cathodoluminescence characterization of ultrathin InN wells/GaN matrix MQWs grown on bulk-GaN and MOVPE-GaN
Comparative cathodoluminescence characterization of ultrathin InN wells/GaN matrix MQWs grown on bulk-GaN and MOVPE-GaN
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DOI：
10.1002/pssc.200880954
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发表时间：
2009-06
期刊：
影响因子：
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通讯作者：
E. Hwang;S. Che;Y. Ishitani;A. Yoshikawa
中科院分区：
文献类型：
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作者：
E. Hwang;S. Che;Y. Ishitani;A. Yoshikawa
One monolayer (1 ML) InN/GaN multiple quantum wells (MQWs) grown on bulk-GaN and MOVPE-GaN/ sapphire substrates with threading dislocation densities (TDDs) of about 106 cm–2 and 108 cm–2, respectively, were characterized by SEM-CL measurements to study the effects of TDs on structural quality of InN/GaN MQWs. For the sample grown on bulk-GaN substrate, step-flow surface morphology and quite uniform spatial emission were observed as compared to the sample grown on MOVPE-GaN/sapphire. CL peak energy at 86 K was observed at around 3.2 eV for both MQWs, but CL emission spectra from MQWs on bulk-GaN substrate were five times stronger with smaller peak energy distribution, and full width at half maximum than those on MOVPE-GaN substrate. This was caused by low-TDD of bulk-GaN substrate. Further, effects of growth temperature on 1 ML InN/GaN MQWs were investigated and it was found that CL peak energy tended to discretely shift to lower energy side, for e.g., from 3.18 eV to 2.9 eV when the growth temperature was decreased from 660 °C to 620 °C. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
